Merc 850 - Removing Powerhead>Shift linkage question

[Bradmph]

Hi,

I have a 1977 Merc 850 and I am removing the powerhead. I have everything removed and I noticed when lifting the head up, the shift linkage connects to a shift shaft that goes down to the lower unit. To remove the upper arm off the top of the shaft in the front of the engine compartment, I need to remove 2 allen (hex) head screws securing it to the shift shaft. Is there a way to access these allen screws more easily. I certainly do not have enough room to lift the powerhead an additional 3 feet up with the shaft just because I can't get my hand contorted enough to reach these 2 allen screws. This linkage connection to the shift shaft is the only thing preventing the head from being removed at this time.




Confusious Say:
"Repairs should always be done in reverse order to prevent the last bolt being installed from always snapping clean off at the head".

 

[Moody Blue]

Re: Merc 850 - Removing Powerhead>Shift linkage question

Shift shaft is a sliding splined joint at the lower unit. No fasteners to remove from the shift shaft.

Powerhead will pull free from the midsection without any connection to the shift shaft. Shift shaft is mounted in and remains attached to the midsection.

 

[chum1]

Re: Merc 850 - Removing Powerhead>Shift linkage question

I just pulled the linkage loose on the left side of the engine (looking forward) and then just pivot it out of the way.Hopefully your going to change the lower bearing cap seals, takes 2 and an oring, seal p/n 470712 you can find them anywhere

 

[Bradmph]

Re: Merc 850 - Removing Powerhead>Shift linkage question

Ok, I am a little confused still and hope we are talking about the same thing.
I removed the 6 locknuts off the downward directed studs on the powerhead that are mounted thru the exhaust plate section. I also had to remove the two nuts from the studs at the front of the motor also. These 2 nuts at the front area would not come completely out until I lifted the powerhead about a 1/4in, which the manual also said would happen when removing the powerhead.
This shift linkage arm is attached to a downward shaft at one end and a sliding linkage arm on the upper end, the shaft goes from that shift linkage arm at the front of the motor area looking forward and the other end stops at about the same level as the prop shaft housing unit if the housing was still attached.

Chum1, are you saying that the linkage arm and that linkage arm shaft will be able to come out of the power head just by lifting on it and turning it as I direct it out from the left side of the motor looking forward?

Here is my diagram of the shaft connection, linkage, etc.

 

[Bradmph]

Re: Merc 850 - Removing Powerhead>Shift linkage question

Ok, I did some investigating and mine aparently has an upper and lower shift shaft and a coupler. To remove this coupler so I can lift the upper shift shaft out with the powerhead looks to need a torch on the coupler if I understand correctly. Is the torch used for expanding the coupler or is there something like soldier mating these shafts to the coupler?

I'll check back after work today and also look at any access panels available on the housings to seperate these shafts easily.

 

[latin monkey]

Re: Merc 850 - Removing Powerhead>Shift linkage question

that shift arm should slide off of the splines at the top of the shift rod at the powerhead as you lift it off. may take a little prying especially if it hasn't been removed in a long time

 

[Bradmph]

Re: Merc 850 - Removing Powerhead>Shift linkage question

Though my eyes are not what they use to be,
It looks like there are 2 tiny (allen) hex head screws on the linkage arm locking it or snugging it to that upper shift shaft. I'm going to try and lift (pry) it loose from the upper shaft today. Though I don't really need the the linkage arm or shaft since this powerhead I am lifting right now is going to replace the one presently on my boat now. If it frustrates me enough I may just cut the upper shaft just below the linkage arm. I'll let ya know either way.

 

[Bradmph]

Re: Merc 850 - Removing Powerhead>Shift linkage question

Well I got the linkage arm and shaft removed. By the way, these screws I thought were allen (HEX) heads was actually just a pin that was pushed into the linkage housing and through the top of the shaft and out flush to the other edge of the link arm. So if any of you folks that have an issue like mine with a lock pin in place on the linkage arm to upper shift shaft...Do Not Pry the linkage arm up off the shaft because it will not work without removing that pin first.
Anyways,
This is how I removed my upper shift shaft and linkage arm on a 1977 850 Mercury Thunderbolt.
It was actually pretty easy after I noticed that if the carbs were removed with their mounting adapter as a unit, the shift shaft and linkage arm slid right up out of the hole. I had to turn the thing a couple times to just clear a couple poke outs on the front of the motor, but the shift shaft was just flexible enough to allow the linkage arm to get by these areas.

Continuing forward, I am now going to start moving my electrics, wiring, hoses, flywheel, etc...from my original powerhead thats mount on the boat now, to this replacement powerhead. So far things are going well for a first time PH replacement on my own.

PS. A gorilla ladder makes a great engine hoist. It is adjustable and very strong enough to hold an engine by a chain while you work.

 

[chum1]

Re: Merc 850 - Removing Powerhead>Shift linkage question

This is how i removed mine with the arm still attached

 

[Moody Blue]

Re: Merc 850 - Removing Powerhead>Shift linkage question

Bradmph, you took the difficult approach but got it done .

I do as chum1 showed in his photo, disconnect the linkage from the powerhead.